JP2004281123A - Heat generating belt and fixing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat generating belt high in heat efficiency and capable of selecting a heat generation region and uniforming the heat transfer to a toner layer, and a fixing device using the belt. <P>SOLUTION: A heat generating belt 10 has a laminated structure composed of an elastic body layer and a release layer on an insulating base layer 11 and a resistance heating element layer 13, and formed in a rig-like shape. An end portion at which the element layer 13 is exposed is made as electricity supply terminals 13a, 13b, and an elliptic area (generation region) 13c generates the heat with a conductive portion of the element layer 13 as a center, when contacting electrodes 21a, 21b on the electricity supplying side with the supply terminals 13a, 13b and supplying electricity. The base layer 11 is composed of a polyimide resin etc. and the thickness is set within a range of 30-100 μm so as to satisfy the condition such as in a mechanical strength. The element layer 13 is composed of a conductive material such as a conductive ceramic, a conductive carbon, and a conductive material, and an insulating material such as an insulating ceramic and a heat-resistance resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat generating belt of a fixing device used for an image forming apparatus such as an electrophotographic copying machine or a printer, and a fixing device using the heat generating belt.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as a conventional electrophotographic copying machine or printer, a photosensitive member is uniformly charged, and an image is exposed thereon to form an image latent image. Then, the formed image latent image is developed with toner to form a toner image of the image, and this is transferred to a recording medium, or once transferred to an intermediate transfer belt, and further transferred to a recording medium, and then transferred to the recording medium. The formed toner image is heated and fixed by a fixing device to form an image.
[0003]
Conventionally, in this type of fixing device, a roller type fixing device including a heating roller having a heat source therein and a pressure roller is generally used, and a high quality of a fixed image can be obtained. In addition to the disadvantage that the start-up time until the surface temperature of the heating roller reaches a temperature suitable for the fixing process is long, the heat capacity is increased due to its structure, and the power consumption for heating is increased. There was a point.
[0004]
Recently, demands for downsizing, speeding up, and energy saving of the image forming apparatus have been further increased, and a heat fixing method using no fixing roller has been developed. As one of the methods, a method using a fixing belt has been proposed.
[0005]
In a fixing device using a fixing belt, as a means for heating the fixing belt, there has been proposed a heating belt in which a belt is provided with a planar heating element to improve thermal efficiency (see Patent Document 1). In this method, since the belt itself generates heat and melts the toner on the recording paper passing through the surface to perform the fixing process, the start-up time until the temperature reaches a temperature suitable for the fixing process is almost zero. The so-called quick start, in which heat fixing can be started immediately, is possible, and there is an advantageous feature that a temperature drop is small and high-speed processing is possible even in continuous paper feeding. Further, since a fixing roller having a large heat capacity is not used, the electric capacity of the heater is reduced, and the power consumption is reduced.
[0006]
[Patent Document 1]
JP-A-2000-66539.
[0007]
[Problems to be solved by the invention]
However, in the fixing device using the heating belt having the above-described sheet heating element, the toner layer adhered on the recording paper is pressed against the hard surface of the sheet heating element, so that heat transfer to the toner layer is not sufficient. It is not suitable as a fixing device of an image forming apparatus for processing a color image such as a color copying machine which requires a large amount of heat for the fixing process due to the non-uniformity of the toner layer and a high image quality, particularly because the toner layer is thick. Have been.
[0008]
In order to improve the melting property of the toner and cope with high-speed processing, the width of the fixing nip formed by the heating belt and the pressure pad is expanded, and the free belt drive that does not wind the heating belt around the roller is also adopted. There is a need to respond. An object of the present invention is to solve the above problems.
[0009]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems, and the invention of claim 1 is a heating belt in which at least an insulating base material layer, a resistance heating element layer and an elastic material layer are laminated, and an end of the insulating base material layer The heating belt is formed such that an end of the resistance heating element layer is exposed from a portion, and the exposed end of the resistance heating element layer is used as a power supply terminal.
[0010]
The heating belt is an annular belt in which an insulating base material layer, a resistance heating element layer, an elastic layer, and a release layer are laminated in this order.
[0011]
Further, the insulating base layer is preferably made of a polyimide resin.
[0012]
According to a fourth aspect of the present invention, at least an insulating base material layer, a resistance heating element layer, and an elastic layer are laminated, and an end of the resistance heating element layer exposed from an end of the insulating base material layer is used as a power supply terminal. An annular heat generating belt, a pressing member disposed inside the annular heat generating belt, for pressing the heat generating belt toward a pressure roller, and disposed outside the annular heat generating belt, between the heat generating belt And a pressure roller forming a fixing nip.
[0013]
The pressing member may be a pad that is in sliding contact with the heating belt or a roller that is in rolling contact with the heating belt.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. A fixing device according to an embodiment of the present invention includes a heating belt and a pressure roller. First, a configuration of a heat generating belt having a plurality of embodiments will be described.
[0015]
FIG. 1 is a cross-sectional view illustrating a layer configuration of a heat generating belt 10 according to the first embodiment of the present invention. The heating belt 10 has a multi-layer laminated structure including an insulating base material layer 11, a resistance heating element layer 13, an elastic body layer 15, and a release layer 16, and is an endless belt, that is, an annular heating belt. is there.
[0016]
FIG. 2 is a front view in which the heat generating belt 10 is developed and viewed from the insulating base material layer 11 side. When the ends where the resistance heating element layer 13 is exposed are used as power supply terminals 13a and 13b, and the electrodes 21a and 21b on the power supply side are brought into contact with the power supply terminals 13a and 13b, power is supplied. The area 13c (hereinafter, referred to as a heat generation area) generates heat.
[0017]
As the electrodes 21a and 21b on the power supply side that come into contact with the power supply terminals 13a and 13b, a roll-shaped electrode or a plate-shaped or bar-shaped electrode that dynamically contacts the power supply terminal can be used. The roll-shaped electrode has an excellent durability, and the bar-shaped electrode has a simple structure and can reduce the manufacturing cost.
[0018]
Next, each layer constituting the heating belt 10 will be described.
[0019]
The insulating base material layer 11 is a layer serving as a base of the heating belt. The insulating base material layer 11 has electrical and thermal insulation properties with respect to pads and rollers described below disposed on the inner surface of the heating belt 10 formed in a ring shape, and prevents current leakage and heat outflow. In addition to its function, it functions to prevent wear due to friction with pads and rollers.
[0020]
The material of the insulating base material layer 11 is mainly made of a polymer such as a polyimide resin and a modified compound thereof, a polyaramid resin and a modified compound thereof, or a silicone resin and a modified compound thereof because of the need to insulate the resistance heating element layer 12, or a polymer of these. It is mainly composed of ingredients.
[0021]
The thickness of the insulating base material layer 11 is preferably in the range of 30 to 100 μm in order to satisfy the required conditions such as thermal conductivity and mechanical strength. Further, in order to improve the heat insulating property to the inner surface, the thermal conductivity of the insulating base material layer 11 is 2.0 W / m · K or less, preferably 1.0 W / m · K or less, more preferably 0.5 W / m · K or less. m · K or less. The volume resistivity of the insulating base material layer 11 is 1 × 10 ⁵ Ω · cm or more, preferably 1 × 10 ⁸ Ω · cm or more, and more preferably 1 × 10 ¹⁵ Ω · cm or more.
[0022]
The resistance heating element layer 13 is a layer that generates Joule heat by supplying power, has a heat resistance of 200 ° C. or more, preferably 300 ° C. or more, and a volume resistance value of 10 ⁻³ to 10 ⁷ Ω · cm, preferably 10 It is in the range of ^-1 to 10 ¹ Ω · cm.
[0023]
The material constituting the resistance heating element layer 13 is a mixture of various conductive materials such as conductive ceramics, conductive carbon, and metal powder, and one to several kinds of insulating materials such as insulating ceramics and heat-resistant resins. The conductive material is adjusted so as to have a predetermined volume resistance value.
[0024]
In this embodiment, as the conductive material, carbon such as C, Ni, Au, Ag, Fe, Al, Ti, Pd, Ta, Cu, Co, Cr, Pt, Mo, Ru, Rh, W, In, etc. In addition to metal materials, VO2, Ru2O, TaN, SiC, ZrO2, InO, Ta2N, ZrN, NbN, VN, TiB2, ZrB2, HfB2, TaB2, MoB2, CrB2, B4C, MoB, ZrC, VC, etc. The compound of.
[0025]
Further, as the heat-resistant resin, polyimide resin, polyaramid resin, polysulfone resin, polyimideamide resin, polyester-imide resin, polyphenylene oxide resin, poly-p-xylylene resin, polybenzimidazole resin, or a resin composed of these derivatives or Various modified resins can be mentioned.
[0026]
Further, as an insulating material used for resistance control and binding, ceramics such as AlN, SiN4, Al2O3, MgO, VO2, SiO2, ZrO2, Bi2O3, TiO2, MoO2, WO2, NbO2, ReO3, etc. A material or the above-mentioned heat-resistant resin is used.
[0027]
Preferred materials for forming the resistance heating element layer 13 include, for example, carbon-dispersed polyimide resin, Ni powder-dispersed silicone resin, Ta-SiO2 mixed ceramic material, and Ru-SiO2 material. The thickness of the resistance heating element layer is usually 20 μm or less, preferably 1 to 5 μm. If the film thickness exceeds 20 μm, there is a disadvantage that the heat generation efficiency with respect to the input power is reduced and the energy consumption is increased.
[0028]
The elastic layer 15 is preferably a soft material having a low rubber hardness, for example, silicone rubber having a JIS-A hardness of 1 to 70 degrees, preferably 5 to 40 degrees. The thickness of the elastic layer 15 is preferably in the range of 50 to 500 μm, more preferably 100 to 300 μm.
[0029]
When the thickness of the elastic layer 15 is less than 50 μm, the fixing belt does not have sufficient elasticity, so that the toner cannot be fixed so as to wrap the toner, and the toner cannot be melted uniformly. It causes unevenness and gloss unevenness, and high image quality cannot be obtained. Further, since the heat capacity may be insufficient, the toner may not be sufficiently melted in the fixing process of a color image with a large toner adhesion amount, which may cause a fixing failure.
[0030]
If the thickness of the elastic layer 15 is larger than 500 μm, the thermal responsiveness of the fixing belt is impaired, which is not preferable.
[0031]
The volume resistance value of the elastic layer 15 is 1 × 10 ⁵ Ω · cm or more, preferably 1 × 10 ⁸ Ω · cm or more, and more preferably 1 × 10 ¹² · cm or more. The thermal conductivity of the elastic layer 15 is 0.1 W / m · K or more, preferably 0.2 W / m · K or more, and more preferably 0.3 W / m in order to improve the heat transfer to the surface.・ K or more is good.
[0032]
The release layer 16 is preferably made of a fluororesin such as PTFE, PFA, or FEP, or a mixture of two or more of these resins can be used in the same manner. The thickness of the release layer 16 is preferably in the range of 5 to 50 μm, more preferably 10 to 30 μm.
[0033]
If the thickness of the release layer 16 is less than 5 μm, the durability is reduced, and if it is more than 50 μm, the effect of providing the elastic layer 15 is lost, which is not preferable.
[0034]
By using a planar resistance heating element for the heating belt and using the exposed portion of the resistance heating element exposed at the end of the heating belt as a power supply terminal, it is possible to selectively generate heat in the heating area of the heating belt, It is also possible to increase the heat efficiency by concentrating the heat generation area in front of the fixing nip. In addition, there is no need for complicated configurations such as patterning the resistance heating element or dividing the resistance heating element and supplying power to each divided area independently, so that the heating area can be selected. can do.
[0035]
Furthermore, since the heat generation area of the heat generation belt is not concentrated at the center, even if the pad configuration is necessary to expand the fixing nip, use a friction-resistant insulating resin such as polyimide resin for the part that slides on the pad. Can be addressed.
[0036]
Further, when the heating belt has a free belt configuration, it is necessary to devise an electrode configuration that contacts the power supply terminal. However, according to this embodiment, the electrode configuration that contacts the power supply terminal can be simply summarized. it can.
[0037]
As described above, the heat generating area of the heat generating belt is an elliptical area centered on the energized portion of the resistance heating element layer, and the surface temperature is not uniform between the central part and the peripheral part of the heat generating belt. By providing an elastic layer on the layer, heat is diffused, the temperature distribution is made uniform, and the amount of heat required for the fixing process can be moved. For this purpose, the elastic layer is made of silicone rubber, fluorine rubber, or the like, and the thickness thereof is required to be at least 100 μm or more, and desirably 200 μm or more. Is preferably 300 μm or less.
[0038]
FIG. 3 is a cross-sectional view illustrating the layer configuration of the heat generating belt 10 according to the second embodiment. The difference from the heat generating belt according to the first embodiment is that the resistance heating element layer 13 and the elastic layer 15 Since an insulating resin layer 14 is provided between them and the other configuration is the same as that of the first embodiment, the same members are denoted by the same reference numerals and detailed description is omitted.
[0039]
By providing the insulating resin layer 14, even if the resistance value of the elastic layer 15 is low, the insulating property can be secured, and the degree of freedom in selecting the material of the elastic layer 15 is increased. That is, for example, when carbon black is blended as a conductive filler in the material of the elastic layer 15, the thermal conductivity of the elastic layer 15 can be increased, so that the heat diffusion efficiency of the surface of the heat generating belt is improved, As a result, temperature unevenness on the surface of the heat generating belt can be reduced.
[0040]
Further, since the protection of the resistance heating element layer 13 is improved by providing the insulating resin layer 14, the durability against the voltage applied to the resistance heating element layer 13 is increased, and a higher voltage can be applied. It becomes.
[0041]
The thickness of the insulating resin layer 14 is desirably set to be thinner than the thickness of the resistance heating element layer 13, and is preferably 50 μm or less.
[0042]
FIG. 4 is a cross-sectional view illustrating the layer configuration of the heat generating belt 10 according to the third embodiment. The difference from the heat generating belt according to the second embodiment is that the insulating base material layer 11 and the resistance heating element layer 13 are different. Since the other configuration is the same as that of the second embodiment, the same reference numerals are given to the same members, and detailed description is omitted.
[0043]
FIG. 5 is a cross-sectional view illustrating the layer configuration of the heat generating belt according to the fourth embodiment. The difference from the heat generating belt according to the first embodiment is that a barrier layer 12 is formed on an insulating base material layer 11. And the resistance heating element layer 13 is provided thereon with an insulating resin layer 14 interposed therebetween. Since the other configuration is the same as that of the first embodiment, the same members are denoted by the same reference numerals. The detailed description is omitted.
[0044]
The barrier layer 12 provided in the embodiment shown in FIGS. 4 and 5 is for preventing moisture from entering the surface of the heat generating belt. As the material of the barrier layer 12, a material such as a metal thin film that does not easily transmit moisture (moisture) is used. By providing the barrier layer, when a resin having high hygroscopicity such as a polyimide resin is used, it is possible to prevent swelling and peeling off of the adhesive.
[0045]
Further, when the barrier layer is made of a metal thin film, the heat conductivity is increased, so that the heat diffusion efficiency on the surface of the heating belt is improved, and as a result, the temperature unevenness on the surface of the heating belt can be reduced.
[0046]
The barrier layer 12 is formed of a film of a polyimide resin or the like on a surface of a film such as iron, copper, zinc, gold, silver, nickel, aluminum, titanium, cobalt, tungsten, molybdenum, stainless steel, or an alloy obtained by appropriately combining these materials. Is formed as a metal thin film by a sputtering method or a vacuum evaporation method, or is formed by screen-printing a conductive paste formed of such a material. The thickness of the barrier layer 12 is 0.2 mm or less. In addition, the barrier layer may be made of a resin material such as a fluororesin which is hardly permeable to moisture.
[0047]
FIG. 6 is a cross-sectional view illustrating a first configuration of a fixing device using the heating belt according to the above-described embodiment. The fixing device 30 shown in FIG. 6 is used as a free tension belt in which the heating belt 10 is used in a tension-free state, that is, in a state in which no tension is applied without being wound around a roller or the like.
[0048]
The heat generating belt 10 is formed as a seamless annular belt in which the insulating base material layer 11 is located inside, and the inner insulating base material layer 11 is a pressing member disposed inside the ring-shaped heat generating belt 10. The outer release layer 16 is placed in sliding contact with the pad 35 so as to contact the pressure roller 31 disposed outside the ring-shaped heating belt 10, and is pressed by the pressure roller 31 by the pad 35. The heating belt 10 is guided by guide members 32, 32 arranged close to the pad 35, and is movably held.
[0049]
The pad 35 is made of a heat-insulating heat-resistant material, for example, silicone rubber, in order to reduce the transmission of heat from the heating belt 10, and the surface that comes into sliding contact with the heating belt 10 is made of a low friction material such as fluororesin. Good. Further, the pressure roller 31 is a roller having a high heat insulating property such as a silicone rubber sponge.
[0050]
Although not shown, the surface temperatures of the heating belt 10 and the pressure roller 31 are detected by a temperature sensor such as a thermistor, and the power supplied to the resistance heating layer 13 of the heating belt 10 is controlled. Is maintained at a predetermined fixable temperature. Although not shown, the heating belt 10 that is in pressure contact with the pressure roller 31 and is in frictional contact with the pressure roller 31 is also driven to move by rotating the pressure roller 31 by a driving device. .
[0051]
The fixing nip N is formed on the contact surface between the heat generating belt 10 and the pressure roller 31, but since the pad 35 is disposed inside the heat generating belt 10, the width of the fixing nip N can be increased, and the speed of the fixing nip N can be increased. Of the fixing process. In addition, when the pressure roller 31 is made of a material having a high heat insulation property, the heat generating belt 10 has an excellent temperature rising characteristic. An apparatus can be provided.
[0052]
FIG. 7 is a cross-sectional view illustrating a second configuration of the fixing device using the heating belt according to the above-described embodiment. The fixing device 40 shown in FIG. 7 also uses the heating belt 10 as a free tension belt that is used in a tension-free state, that is, in a state where no tension is applied.
[0053]
The difference from the second configuration of the fixing device described with reference to FIG. 6 is that the pad 35 serving as a pressing member is replaced with a pressing roller 37, and the other configuration is the same. The same reference numerals are given and detailed description is omitted.
[0054]
The pressing roller 37, which is a pressing member, is made of a heat-insulating heat-resistant material, for example, silicone rubber, in order to reduce the transmission of heat from the heat generating belt 10. The surface in contact with the heat generating belt 10 has a low surface made of fluororesin or the like. It is preferable to use a friction material.
[0055]
When the pressing roller 37 is used instead of the pad 35, the width of the fixing nip N is smaller than when the pad 35 is used. Since the rolling contact is made instead of the sliding contact, the life of the heating belt 10 can be extended.
[0056]
FIG. 8 is a cross-sectional view illustrating a third configuration of the fixing device using the heating belt according to the above-described embodiment. In the fixing device 50 illustrated in FIG. 8, the heat generating belt 10 is configured such that the insulating base layer 11 inside the heat generating belt 10 contacts two pressing rollers 39, 39 which are pressing members disposed inside the annular heat generating belt 10. The outer release layer 16 is disposed so as to contact a pressure roller 31 disposed outside the ring-shaped heating belt 10, and is pressed toward the pressure roller 31.
[0057]
According to this configuration, the area where the heating belt 10 and the pressure roller 31 are in contact with each other is increased, and the width of the fixing nip N can be increased. Further, the contact state between the heat generating belt 10 and the pressing rollers 39, 39 is not a sliding contact as in the case of the pad 35 but a rolling contact, so that the life of the heat generating belt 10 can be extended.
[0058]
The embodiments of the invention described above include the inventions described below.
(1) The heat generating belt according to claim 1, wherein the insulating base layer is an insulating base layer for electrically and thermally insulating the resistance heating element layer.
(2) The heat generating belt according to claim 1, wherein the thickness of the insulating base material layer is in a range of 30 to 100 μm which satisfies required conditions such as thermal conductivity and mechanical strength. Fever belt.
(3) The heat generating belt according to (1), wherein the elastic layer has a volume resistivity of 1 × 10 ⁵ Ω · cm or more and a thermal conductivity of 0.1 W / m · K or more. belt.
[0059]
【The invention's effect】
As described in detail above, the heat generating belt according to claim 1 of the present invention is a heat generating belt in which at least an insulating base material layer and a resistance heating element layer are stacked, and the heat generating belt extends from an end of the insulating base material layer. The end of the resistance heating element layer is formed to be exposed, and the exposed end of the resistance heating element layer is used as a power supply terminal.
[0060]
With this configuration, the heat generation area of the heat generation belt can be selectively heated, and the heat generation area can be concentrated in front of the fixing nip to increase the heat efficiency, and the heat transfer to the toner layer can be made uniform. In particular, the present invention can be applied to a heat generating belt of a fixing device of an image forming apparatus for processing a color image such as a color copying machine which requires a large amount of heat for the fixing process because the toner layer is thick and requires high image quality.
[0061]
According to a fourth aspect of the present invention, there is provided a fixing device using the heat generating belt according to the first aspect, wherein a heat generating region of the heat generating belt is selected by pressing the heat generating belt against a pressing roller with a pressing member. In addition to this, it is possible to provide a fixing device capable of generating heat, increasing the width of the fixing nip, improving the melting property of the toner, increasing the thermal efficiency, and supporting high-speed processing.
[Brief description of the drawings]
FIG. 1 is a sectional view illustrating a layer configuration of a heat generating belt according to a first embodiment.
FIG. 2 is a front view of the heat generating belt as viewed from an insulating base material layer side.
FIG. 3 is a sectional view illustrating a layer configuration of a heat generating belt according to a second embodiment.
FIG. 4 is a sectional view illustrating a layer configuration of a heat generating belt according to a third embodiment.
FIG. 5 is a sectional view illustrating a layer configuration of a heat generating belt according to a third embodiment.
FIG. 6 is a cross-sectional view illustrating a first configuration of the fixing device.
FIG. 7 is a cross-sectional view illustrating a second configuration of the fixing device.
FIG. 8 is a cross-sectional view illustrating a third configuration of the fixing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Heating belt 11 Insulating base material layer 12 Barrier layer 13 Resistance heating element layer 14 Insulating resin layer 15 Elastic layer 16 Release layer 30, 40, 50 Fixing device 31 Pressure roller 32 Guide member 35 Pad (pressing member)
37 pressing roller (pressing member)
39 pressing roller (pressing member)

Claims (5)

At least an insulating base layer, a heating belt in which a resistance heating element layer and an elastic body layer are laminated, and formed such that an end of the resistance heating element layer is exposed from an end of the insulating base layer, A heating belt, wherein the exposed end of the resistance heating element layer is used as a power supply terminal. The heating belt according to claim 1, wherein the heating belt is an annular belt in which an insulating base material layer, a resistance heating element layer, an elastic body layer, and a release layer are laminated in this order. The heating belt according to claim 1, wherein the insulating base material layer is a polyimide resin. At least an insulating base material layer, a resistance heating element layer and an elastic body layer are laminated, and an annular heating belt having an end of the resistance heating element layer exposed from an end of the insulating base layer as a power supply terminal,
A pressing member that is arranged inside the annular heat generating belt and presses the heat generating belt toward a pressure roller,
A pressure roller disposed outside the annular heating belt and forming a fixing nip with the heating belt. 5. The fixing device according to claim 4, wherein the pressing member is a pad that is in sliding contact with the heating belt or a roller that is in rolling contact with the heating belt.

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